During open heart surgeries, such as coronary artery bypass graft, valve repair surgeries, thoracic aneurysm repair, removal of atrial myxoma, and septal defect repairs, currently the most common method of temporarily occluding the ascending aorta utilizes a mechanical cross clamp. Aortic occlusion is needed to establish isolation of coronary circulation from the peripheral circulatory system during cardiac arrest, so that peripheral organs would not be paralyzed by cardioplegic solution. An arterial cannula is commonly inserted in a patient's aorta or femoral artery to provide return of oxygenated blood from a bypass-oxygenator machine, whereas a venous catheter is inserted into the right atrium, superior vena cava, or inferior vena cava to carry deoxygenated blood from the heart to a bypass-oxygenator machine. Other less common means of occluding the aorta include percutaneous balloon catheter occlusion, direct aortic balloon catheter (Foley) occlusion, aortic balloon occluder cannula, and an inflating diaphragm occluder (Hill--occlusion trocar).
Manipulation of ascending aorta during mechanical cross-clamping or other means of aortic occlusion often dislodges atheromatous plagues from the ascending aorta downstream to peripheral organs. Tissue debris, air, or calcium plaques may also arise from cardiac manipulation. Embolization of atheromatous plaques, tissue debris, or calcium plaques may lead to stroke, organ death or ischemia.
Devices for filtering blood have been designed to reduce a patient's peri-operative risk of peripheral embolization, thereby reducing surgical morbidity and mortality. The vast majority of these devices are designed for permanent placement in veins, in order to trap emboli destined for the lungs, e.g., Kimmell, Jr., U.S. Pat. No. 3,952,747, Cottenceau et al., U.S. Pat. No. 5,375,612, Gunther et al., U.S. Pat. No. 5,329,942, and Lefebvre, French Patent No. 2,567,405, incorporated herein by reference. Few intravascular devices are designed for arterial use, e.g., Ginsburg, U.S. Pat. No. 4,873,978, Ing. Walter Hengst GmbH & Co, German Patent DE 34 17 738, da Silva, Brazil Patent Application No. PI9301980A, and Barbut et al, U.S. Pat. No. 5,769,816, all incorporated herein by reference, have been developed to entrap arterial emboli during open-heart procedures.
The aforementioned devices all have drawbacks in that a filter or membrane to entrap emboli is deployed by means of an umbrella mechanism, thereby failing to accurately follow the rough non-uniform contour of the internal blood vessel wall. A built-in spring offers the force to bring the frame into contact with the vessel wall. The umbrella frame, however, would segment the contact, thereby only assuring a seal at each discrete arm in contact. Moreover, in using the current filter devices, an operator has little or no feel for contact between the filter mechanism and the vessel wall. Further, current designs do not permit closure which is sufficiently tight and secure to prevent release of entrapped emboli.
A need exists for devices and methods which provide contact of medical devices and vessel walls with minimum gap, give an operator a feel for the vessel wall during deployment, and permit efficient and secure closure to ensure retention of entrapped debris.